The present invention relates to the field of communications electronics, and, more particularly, to a switched communications device and related methods.
Digital communications over twisted copper wire pairs, or optical fiber pairs, are widely used for Local Area Networks (LANs), for example. The LAN typically connects multiple computer users to a server or other computer. A LAN transceiver, that is, a combination transmitter and receiver, is typically used to transmit data and receive data over the twisted pair or fiber pair.
A typical LAN 15 as in the prior art is shown in FIG. 1. The LAN 15 includes a pair of servers 16 connected to a plurality of user workstations 21. A hub 17 is connected on one side to the servers 16, and on the other side to the workstations 21. The hub 17 includes signal transceivers and associated circuitry for processing the signals between the servers 16 and workstations 21.
A simplified prior art hub 17 with the overall housing removed for clarity is shown in FIG. 2. More particularly, the illustrated hub 17 includes a modular jack connector 22, which, in turn, may provide twelve ports 22a for connection to up to twelve workstations 21. A series of electrical conductors, not shown, are carried within each recess of the modular jack connector 22 and engage mating conductors on the corresponding jack or plug. One common port arrangement provides compatibility with a so-called xe2x80x9cRJ-45xe2x80x9d jack. Optical ports, such as including an optical detector and optical emitter, are also commonly used to establish inbound and outbound signal paths.
The modular jack connector 22 is mounted onto a mother circuit board 24. The mother circuit board 24 also illustratively mounts three communications processors 26, such as may be provided by available integrated circuit packages. In addition, the mother board 24 illustratively mounts associated magnetic devices 27 for coupling to twisted wire pairs, for example. The magnetic devices 27 are typically small transformers.
The communications processor IC""s 26 may be integrated quad-port repeaters such as the Model LXT915 available from Level One of Sacramento, Calif. Each of the communications processors 26 includes four transceivers for connection to four respective ports 22a. The communications processor IC""s establish switched communications among the connected ports. Alternately, the communications processors may be integrated quad transceivers providing switched communication between ports. For example, each communications processor may be a Model AH104-QF ethernet transceiver available from Adhoc Technologies of San Jose, Calif.
The mother circuit board 24 would also typically mount a number of other components, not shown, such as for supplying power, providing various status indications, etc. An overall housing, not shown, would also typically be provided to protect the mother board 24 and other components. The hub 17 is typically a relatively bulky and expensive piece of equipment.
Board-mounted shielding would typically be needed to shield the communications processors 26 from the magnetic devices 27. The magnetic devices 27 typically generate electromagnetic interference (EMI), and the communications processors 26 are typically susceptible to EMI. The housing may be made of an electrical conductor, to provide an overall EMI shield.
Another disadvantage of prior art LANs including one or more conventional hubs 17, is that the hubs are separate pieces of equipment from the servers 16. The hubs 17 need to be purchased, installed and maintained. In other words, the hubs 17 add cost and complexity, and may reduce the overall reliability of the LAN 15.
In view of the foregoing background, it is therefore an object of the present invention to provide a switched communications device and associated method wherein the functions of a conventional hub can be provided in a more compact and convenient device, such as to be integrated in another device, to thereby reduce cost and increase reliability.
It is another object of the invention to provide such a switched communications device and associated method which is also resistant to EMI and which can be readily compatible with existing RJ-45 jacks and plugs.
These and other objects, features and advantages in accordance with the present invention are provided by a switched communications device comprising, in one embodiment, a multi-port jack housing having a front and a back, and including portions defining a plurality of recesses extending inwardly from the front for receiving respective mating plugs therein. Signal connector means are preferably positioned within each of the recesses and define a respective plurality of communications ports. Of course, each communications port establishes inbound and outbound signal paths with a respective mating plug. A circuit board is positioned within the multi-port jack housing and preferably extends adjacent the back thereof.
In addition, the switched communications device preferably includes at least one switched communications processor mounted on the circuit board and connected to the plurality of communications ports for processing inbound and outbound communications signals so that the signals are switched among the communications ports. In other words, the at least one switched communications processor preferably communicates with two or more of the communications ports in a switched fashion so that signals appear at the connected communications ports. Accordingly, an extremely compact switched communications multi-port device is provided.
Two or more of the plurality of recesses may be positioned in side-by-side relation. In one particularly advantageous embodiment, the recesses are arranged in two tiers, with each tier comprising two or more recesses arranged in sideby-side relation. In addition, a respective switched communication processor may be provided for each group of four communications ports. Each switched communications processor preferably includes an integrated circuit. Each switched communications processor also preferably includes a plurality of transceivers for a corresponding group of communications ports.
Another important aspect of the invention relates to shielding. More particularly, the circuit board preferably comprises an electrically conductive layer defining a first internal electromagnetic interference (EMI) shield. In embodiments wherein a plurality of switched communications processors are used, these are all preferably positioned on a first side of the circuit board. Moreover, EMI generating devices, such as circuit magnetics, are preferably positioned on the second side of the circuit board. Accordingly, a compact arrangement is facilitated without compromising performance caused by EMI.
Also relating to EMI, the switched communications device may preferably include an electrically conductive layer on outer surface portions of the multi-port jack housing defining an external EMI shield. This external EMI shield may be connected to the internal EMI shield.
There is a large installed base of existing communications ports and equipment compatible with the RJ-45 jack. Accordingly, in the switched communications device according to the invention each of the communications ports is preferably compatible with the RJ-45 jack.
The signal connector means may comprise a plurality of electrical contacts, such as for twisted pair links. Alternately, the signal connector means may be optical and comprise an optical detector for inbound optical signals, and an optical emitter for outbound optical signals. Mixes of both formats may be provided in the communications device.
Another aspect of the invention relates to a method for making a switched communications device comprising a multi-port jack housing having a front and a back, and including portions defining a plurality of recesses extending inwardly from the front for receiving respective mating plugs therein. The method preferably comprises the steps of: positioning signal connector means within each of the recesses and defining a respective plurality of communications ports, each communications port for establishing inbound and outbound signal paths with a respective mating plug; mounting at least one switched communications processor on a circuit board and connected to the plurality of communications ports for processing inbound and outbound communications signals so that signals are switched among the ports; and positioning the circuit board within the multi-port jack housing and extending adjacent the back thereof.